Index: twisted/scripts/_twistw.py
===================================================================
--- twisted/scripts/_twistw.py	(revision 27398)
+++ twisted/scripts/_twistw.py	(working copy)
@@ -2,10 +2,22 @@
 # Copyright (c) 2001-2008 Twisted Matrix Laboratories.
 # See LICENSE for details.
 
-from twisted.python import log
+import os
+import sys
+import msvcrt
+
+try:
+    import win32api
+    import win32con
+    import win32process
+    import win32security
+    import win32service
+except ImportError:
+    win32process = None
+
+from twisted.python import win32
 from twisted.application import app, service, internet
 from twisted import copyright
-import sys, os
 
 
 
@@ -24,6 +36,87 @@
 
 
 
+def getPythonArgs():
+    """
+    Return the list of command line args that were used to start
+    the current Python interpreter and were not stored in C{sys.argv}.
+
+    These are the options that control the Python interpreter itself,
+    like the Python executable, optimization level, warning filters,
+    division behaviour and literal string handling.
+    """
+    args = [sys.executable]
+    for warnoption in sys.warnoptions:
+        args.append("-W")
+        args.append(warnoption)
+    if type(1 / 2) is not int:
+        args.append("-Qnew")
+    if type("") is not str:
+        args.append("-U")
+    if not __debug__:
+        if getPythonArgs.__doc__ is None:
+            args.append("-OO")
+        else:
+            args.append("-O")
+    return args
+
+
+
+def daemonize():
+    args = [os.path.abspath(__file__)] + sys.argv
+    executable = sys.executable
+    cmdline = win32.quoteArguments(getPythonArgs() + args)
+    inherit = False
+    priority = win32process.GetPriorityClass(win32process.GetCurrentProcess())
+    flags = (win32process.CREATE_BREAKAWAY_FROM_JOB | # session leader
+             win32process.CREATE_NEW_PROCESS_GROUP |  # group leader
+             win32process.DETACHED_PROCESS |          # no controlling terminal
+             priority)
+    info = win32process.STARTUPINFO()
+    win32process.CreateProcess(executable, cmdline, None, None,
+                               inherit, flags, None, None, info)
+    # Do what exec* functions do, let the OS do the cleanup.
+    os._exit(0)
+
+
+
+def daemonize2():
+    args = [sys.argv[1], "--nodaemon"] + sys.argv[2:]
+    executable = sys.executable
+    cmdline = win32.quoteArguments(getPythonArgs() + args)
+    inherit = True
+    priority = win32process.GetPriorityClass(win32process.GetCurrentProcess())
+    flags = (win32process.CREATE_NO_WINDOW | # create an invisible console
+             win32process.CREATE_NEW_PROCESS_GROUP | # group leader
+             priority)
+    attributes = win32security.SECURITY_ATTRIBUTES()
+    attributes.bInheritHandle = True
+    station = win32service.CreateWindowStation(None, 0,
+                                               win32con.GENERIC_READ |
+                                               win32con.GENERIC_WRITE,
+                                               attributes)
+    station.SetProcessWindowStation()
+    sname = win32service.GetUserObjectInformation(station,
+                                                  win32service.UOI_NAME)
+    dname = str(os.getpid())
+    desktop = win32service.CreateDesktop(dname, 0,
+                                         win32con.GENERIC_READ |
+                                         win32con.GENERIC_WRITE,
+                                         attributes)
+    desktop.SetThreadDesktop()
+    null = os.open("NUL", os.O_RDWR)
+    handle = msvcrt.get_osfhandle(null)
+    info = win32process.STARTUPINFO()
+    info.lpDesktop = "%s\\%s" % (sname, dname)
+    info.dwFlags = win32process.STARTF_USESTDHANDLES
+    info.hStdInput = info.hStdOutput = info.hStdError = handle
+    win32process.CreateProcess(executable, cmdline, None, None,
+                               inherit, flags, None, None, info)
+    # Same as above, exit as fast as posible.
+    os._exit(0)
+
+
+
 class WindowsApplicationRunner(app.ApplicationRunner):
     """
     An ApplicationRunner which avoids unix-specific things. No
@@ -34,17 +127,55 @@
         """
         Do pre-application-creation setup.
         """
+        self.config['nodaemon'] = (self.config['nodaemon']
+                                   or self.config['debug'])
         self.oldstdout = sys.stdout
         self.oldstderr = sys.stderr
-        os.chdir(self.config['rundir'])
 
 
     def postApplication(self):
         """
         Start the application and run the reactor.
         """
-        service.IService(self.application).privilegedStartService()
-        app.startApplication(self.application, not self.config['no_save'])
+        self.startApplication(self.application)
+        self.startReactor(None, self.oldstdout, self.oldstderr)
+
+
+    def startApplication(self, application):
+        """
+        Configure global process state based on the given application and run
+        the application.
+
+        @param application: An object which can be adapted to
+            L{service.IService}.
+        """
+        self.setupEnvironment(self.config['rundir'], self.config['nodaemon'])
+        service.IService(application).privilegedStartService()
+        app.startApplication(application, not self.config['no_save'])
         app.startApplication(internet.TimerService(0.1, lambda:None), 0)
-        self.startReactor(None, self.oldstdout, self.oldstderr)
-        log.msg("Server Shut Down.")
+
+
+    def setupEnvironment(self, rundir, nodaemon):
+        """
+        Set the working directory, and daemonize.
+
+        @type rundir: C{str}
+        @param rundir: The path to set as the working directory.
+
+        @type nodaemon: C{bool}
+        @param nodaemon: A flag which, if set, indicates that daemonization
+            should not be done.
+        """
+        daemon = not nodaemon and win32process is not None
+        if daemon:
+            daemonize()
+        elif win32process is not None:
+            # Restore standard SIGINT handling lost during daemonization
+            win32api.SetConsoleCtrlHandler(None, 0)
+        # Note: This needs to come after daemonization,
+        # otherwise we would change working dir twice.
+        os.chdir(rundir)
+
+
+if __name__ == "__main__":
+    daemonize2()